PROMETHAZINE

Highly Sedative, First Generation Antihistamine

Cross and Allergic Reactions

Usage

Amoxicillin should not be taken if one has- Mononucleosis, Colitis, Diabetes, Renal Dysfunction, Pku (Phenylketonuria), Hemodialysis--Dose needs to be decreased when in pregnancy

Type

It is a Highly Sedative antihistaminic.

Promethazine acts by blocking the H1 receptor.

They block histamines inducing- bronchoconstriction, intestinal contraction and smooth muscle contraction

They act against wheal, flare and itch
It prevents and treats allergic reactions such as urticaria, angioedema and itching
It can also cause CNS depression
High anticholinergic action

History

Promethazine was developed in the mid 1940s by a team of scientists from Rhône-Poulenc laboratories.

Usage

It is commonly used -

For allergic reactions such as urticaria or angioedema
For prevention of vomiting in pregnancy
Preventing motion sickness
Reduce tremor, rigidity and sialorrhea(dripping saliva) in patients with parkinsonism
Works against vertigo
used as Preanaesthetic medicine in children

Cross and Allergic Reactions

Promethazine cross reacts with other antihistamines, but has no allergic reactions.

Promethazine reacts with Alcohol(Alcohol will increase dizziness, drowsiness, and difficulty concentrating. Some people may also experience impairment in thinking and judgment.) and CNS depressants.

Side Effects

The Side Effects of Promethazine are -

Drowsiness,
Dry mouth, constipation, blurring of vision, difficulty urinating or headache.
In children, stomach pain and vomiting may occur.
Fall in BP with injectable form
Some people may become restless, excited and are unable to sleep
Can cause convulsions at toxic dose

Should not be taken if

Should not take if one has- CNS depression, respiratory depression or heart failure

Shelf Life

Shelf Life:- 3 years from manufacturing date.

90% drugs(approved by the FDA) are perfectly good even 15 years after the expiry date, the only exception to this may be tetracycline. If the drugs are kept in a cool environment, like a fridge then they can be used even longer. The expiry date only marks that now there isn’t 100% effectiveness.